• Title/Summary/Keyword: crystal alignment

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Novel Technique for Splay to Bend Transition in a ${\pi}$ Cell

  • Jhun, Chul-Gyu;Lee, Jong-Lac;Kang, Sang-Ho;Lee, Seong-Ryong;Kim, Jae-Chang;Yoon, Tae-Hoon
    • Journal of Information Display
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    • v.5 no.2
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    • pp.19-22
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    • 2004
  • A ${\pi}$ cell is initially in splay state. Before driving a ${\pi}$ cell, transition from splay to bend state is always necessary which originates from nucleation. We propose a novel technique to make bend transition fast and effectively by forming transition cores around the pixels with the technique of multi-domain alignment, where domain boundaries play a crucial role in splay to bend transition. This noble technique enables the splay to bend transition to occur within less than 2 seconds with a low applied voltage.

Preparation of epitaxial bismuth titanate thin films by the sol-gel process (졸-겔법을 이용한 Epitaxial Bismuth Titanate 박막의 제조)

  • 김상복;이영환;윤연흠;황규석;오정선;김병훈
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.13 no.2
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    • pp.56-62
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    • 2003
  • Epitaxial $Bi_4Ti_3O_{12}$ films on $SrTiO_3$(100), L$aA1O_3$(100) and MgO(100) were prepared by sol-gel process using metal naphthenate as a starting material. As-deposited films were pyrolyzed at $500^{\circ}C$ for 10 min In air and annealed at $750^{\circ}C$ for 30 min in air. Crystallinity and in-plane alignment of the film were investigated by X-ray diffraction $\theta$-2$\theta$ scan and P scanning. A field emission-scanning electron microscope and an atomic force microscope were used for characterizing the surface morphology and the surface roughness of the film. The film prepared on MgO(100) showed the most poor crystallinity and in-plane alignment, compared to those on the other substrates. While the films on $LaA1O_3$(100) and $SrTiO_3$(100) having high crystallinity and in-plane alignment showed the form of columnar grain growth, the film on MgO(100) which had poor crystallinity showed the form of acicula grain growth.

Enhanced Performance in a Lithium-ion Battery via the Crystal-aligned LiNi0.6Mn0.2Co0.2O2 and the Relevant Electrochemical Interpretation (결정배향 LiNi0.6Mn0.2Co0.2O2 전극활물질을 통한 리튬이차전지 성능 향상 및 이의 전기화학적 해석)

  • Cham, Kim
    • Journal of the Korean Chemical Society
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    • v.66 no.6
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    • pp.451-458
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    • 2022
  • Through the crystal alignment research based on the magnetic properties of LiNixMnyCo1-(x+y)O2 such as magnetic susceptibility and related anisotropy, a crystal aligned LiNi0.6Mn0.2Co0.2O2 electrode is obtained, in which the (00l) plane is frequently oriented perpendicular to the surface of a current collector. The crystal aligned LiNi0.6Mn0.2Co0.2O2 electrode steadily exhibits low electrode polarization properties during the charge/discharge process in a lithium-ion battery, thus affording an improved capacity compared to a pristine LiNi0.6Mn0.2Co0.2O2 electrode. The aligned LiNi0.6Mn0.2Co0.2O2 electrode may have an appropriate structural nature for fast lithium-ion transport due to the oriented (00l) plane, and thus it contributes to enhancing the battery performance. This enhancement is analyzed in terms of various electrochemical theories and experiment results; thus, it is verified to occur because of the considerably fast lithium-ion transport in the aligned LiNi0.6Mn0.2Co0.2O2 electrode.

The Alignment of Liquid Crystals on the Film Surfaces of Soluble Aromatic Polyimides Bearing t-Butylphenyl and Trimethylsilylphenyl Side Groups

  • Hahm, Suk-Gyu;Jin, Kyeong-Sik;Park, Sam-Dae;Ree, Moon-Hor;Kim, Hyung-Sun;Kwon, Soon-Ki;Kim, Yun-Hi
    • Macromolecular Research
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    • v.17 no.12
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    • pp.976-986
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    • 2009
  • With the study goal of firstly elucidating the anisotropic interactions between oriented polymer chain segments and liquid crystal (LC) molecules, and secondly of determining the contributions of the chemical components of the polymer segments to the film surface topography, LC alignment, pretilt, and anchoring energy, we synthesized three dianhydrides, 1,4-bis(4'-t-butylphenyl)pyromellitic dianhydride (BBPD), 1,4-bis(4'-trimethylsilylphenyl)pyromellitic dianhydride(BTPD), and 2,2'-bis(4"-tert-butylphenyl)-4,4',5,5'-biphenyltetracarboxylic dianhydride (BBBPAn), and a series of their organosoluble polyirnides, BBPD-ODA, BBPD-MDA, BBPD-FDA, BTPD-FDA, and BBBPAn-FDA, which contain the diamines 4,4'-oxydianiline (ODA), 4,4'-methylenediamine (MDA), and 4,4'-(hexafluoroisopropylidene)dianiline (FDA). All the polyimides were determined to be positive birefringent polymers, regardless of the chemical components. Although all the rubbed polyimide films exhibited microgrooves which were created by rubbing process, the film surface topography varied depending on the polyimides. In all the rubbed films, the polymer chains were unidirectionally oriented along the rubbing direction. However, the degree of in-plane birefringence in the rubbed film varied depending on the polyimides. The rubbing-aligned polymer chains in the polyimide films effectively induced the alignment of nematic LCs along their orientation directors by anisotropic interactions between the preferentially oriented polymer chain segments and the LCs. The azimuthal and polar anchoring energies of the LCs ranged from $0.45{\times}10^{-4}\;-\;1.37{\times}10^{-4}\;J/m^2$ and from $0.86{\times}10^{-5}\;-\;4.26{\times}10^{-5}\;J/m^2$, respectively, depending on the polyimides. The pretilt angles of the LCs were in the range $0.10-0.62^{\circ}$. In summary, the soluble aromatic polyimides reported here are promising LC alignment layer candidates for the production of advanced LC display devices.

Liquid Crystal Aligning Capabilities in the Photoaligned TN-Cell on Blending Photopolymer (복합 광폴리머 표면을 이용한 장배향 TN 셀의 액정배향 특성)

  • Hwang, Jeoung-Yeon;Jo, Yong-Min;Seo, Dae-Shik;Suh, Dong-Hack
    • Proceedings of the KIEE Conference
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    • 2001.11a
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    • pp.178-181
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    • 2001
  • The electro-optical (EO) characteristics for the twisted-nematic (TN)-liquid crystal display (LCD) photo-aligned with polarized UV exposure on various blending photopolymer surfaces were investigated. Excellent LC alignment and voltage-transmittance (V-T) characteristics for TN-LCD photo-aligned with polarized UV exposure of normal incidence on the blending Photopolymer (polyimide (PI) + PM4Ch (poly(4-methacryloyloxy chalcone))) surface containing chalcone group can be achieved. The EO performances of the TN-LCD photo-aligned on the blending photopolymer can be improved due to the photosensitivity by long side chain of the photopolymer.

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Nanotransfer Printing for Large-Scale Integrated Nanopatterns of Various Single-Crystal Organic Materials

  • Baek, Jang-Mi;Park, Gyeong-Seon;Seong, Myeong-Mo
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.361.2-361.2
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    • 2016
  • The manufacture of organic electronic circuits requires effective heterogeneous integration of different nanoscale organic materials with uniform morphology and crystallinity in a desired arrangement on a substrate. Herein, we present a new direct printing method, which enables monolithic integration of crystalline nanowire arrays with a diverse range of organic materials. In this method, we use a nanoscale patterned soft mold, which contains an assembly of simple nanoline patterns but, in combination with droplet of various organic inks, can produce a large-scale integration of various nanopatterns with multiple kinds of organic materials. The morphology of organic nanowires can controlled by nanoconfinement in nanoline of mold. And mutual alignment of nanopatterns can be controlled by adjusting the ink droplet size, number of droplets, ink deposition locations.

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Transflective IPS LCD with Multi-Domain Structures

  • Park, Kyoung-Ho;Ko, Young-Jo;Kim, Jung-Hyoung;Kim, Jae-Chang;Yoon, Tae-Hoon
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.895-898
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    • 2004
  • We propose configurations for a transflective in-plane switching (IPS) cell using muti-domain structures. Usually, the cell configurations for a transflective liquid crystal(LC) cell have a complicated structure, because retardation change of transmissive part and reflective part are not same. The transflective LC cell should have two configurations for each part, such as a multi-cell gap structure. With the ion-beam alignment and the horizontal switching LC cell, a simple structure for a transflective LC cell is proposed. The configuration only adopts one cell gap structure, which may help the enhancement of a yield. Their original optical properties in conventional transmissive and reflective type IPS liquid crystal dispaly(LCD) are kept, it shows the wide-viewing angle and the good wavelength dispersion characteristics.

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Electro-optic Characteristics on Photoaligned TN Cell using Photopolymer Based Hydroxy Aromatic Polyimide (Hydroxy Aromatic Polyimide계 광폴리머 표면을 이용한 광배향 TN 셀의 전기광학 특성)

  • Lee, Whee-Won;Hwang, Jeoung-Yeon;Choi, Sung-Ho;Suh, Dong-Hack;Seo, Dae-Shik
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.10
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    • pp.924-928
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    • 2005
  • We synthesized the two types of photoalignment material of high thermal resistance with hydroxyl aromatic polyimide, and studied the liquid crystal (LC) aligning capabilities on the photopolymer layers. Also, electro-optical (EO) performances for the twisted-nematic (TN)-liquid crystal display (LCD) photoaligned with linearly polarized UV exposure were investigated. A good LC alignment with UV exposure on the two types of photopolymer surface can be obtained. The Voltage-transmittance (V-T) curve in the photoaligned TN cell with UV exposure was different from two type. The response time of photoaligned TN cell was measured about 21 ms in two alkyl chain and about 15 ms in four alkyl chain.

Development of Low Anchoring Strength Liquid Crystal Mixtures for Bistable Nematic Displays

  • Dozov, Ivan;Stoenescu, Daniel-Nicusor;Lamarque-Forget, Sandrine;Joly, Stephane;Dubois, Jean-Claude;Martinot-Lagarde, Philippe
    • Journal of Information Display
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    • v.6 no.3
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    • pp.1-5
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    • 2005
  • The recent Bistable Nematic ($BiNem^{(R)}$) LCD technology presents long term bistability, high level passive matrix multiplexing, gray levels capabilities and high optical quality. The $BiNem^{(R)}$ device, based on anchoring breaking, needs specific low anchoring strength materials - alignment layers and liquid crystal mixtures. We present here our approach to develop nematic mixtures with wide enough temperature range and low zenithal anchoring energy.

Ultra Thin Reflective Flexible Liquid Crystal Display

  • Liu, Kang-Hung;Kuo, Chia-Wei;Ku, Chun-Kang;Chang, Chih-Yuan;Liao, Chi-Chang
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.1080-1082
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    • 2008
  • An ultra-thin reflective flexible LCD film has been demonstrated. The 30% thickness of the display can be reduced by applying a quarter-wave-plate film as upper substrate. A low temperature alignment material and special designed photo spacer were applied in this new display. The bending behavior was improved by reduced thickness.

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